1. Field of the Invention
The present invention, in general, relates to the field of mobile communication technology. The invention relates to Evolution Data Only/Evolution Data Optimized (EVDO) and its evolved communication systems having multiple protocol revisions. It describes a system and method for efficiently operating in a system in which the access terminal is moving across access networks supporting different protocol revisions. More particularly, the invention relates to a system and method for inter-working in a multi protocol revision based EVDO communication systems.
2. Description of the Related Art
The following terms are used throughout this application as follows:
Access Network: The network equipment which provides data connectivity between a packet switched data network (typically the Internet) and access terminals.
Access Terminal: A device providing data connectivity to a user. An access terminal may be connected to a computing device such as a laptop personal computer or it may be a self-contained data device such as a Personal Digital Assistant (PDA). An access terminal is equivalent to a mobile station.
EV-DO: CDMA2000 1× evolution-Data Optimized system.
MAC: Medium Access Control Protocol
The EVDO communication system consists of several protocols and applications, which define the procedures to be followed by the Access Network (AN) and the Access Terminal (AT) to communicate with each other. Each protocol/application has several subtypes. A subtype of a protocol/application defines a distinct procedure to be used for the operation of that protocol/application. Each subtype of a protocol/application contains several configurable attributes, which govern its operation. The EVDO communication system provides procedure to negotiate and configure the protocol/application subtypes and their corresponding attributes between the AT and AN. Configuration Request and Configuration Response messages are exchanged between AT and AN to negotiate protocol/application subtypes and their corresponding attributes.
The set of negotiated and configured protocol/application subtypes and the corresponding attributes constitutes an EVDO session. In other words, an EVDO session refers to a shared state between the AT and the AN. This shared state stores the protocols/applications and the protocol/application configurations that were negotiated and are used for communications between the AT and the AN. Session Configuration Protocol (SCP) defines the procedure to negotiate and configure multiple EVDO sessions. These multiple EVDO sessions negotiated and configured by SCP are also referred to as multiple personalities. Each personality configured is identified by a personality index. At a given point of time only one personality will be in use between the AT and AN. The personality index in use is stored in a Session Configuration Token (SCT).
Each protocol/application can have two instances, InConfiguration and InUse instances. An InUse instance is the working instance of a protocol/application. At power-up, an EVDO session constitutes default set of Protocol and Application subtypes and also default values for attributes of these Protocols and Application subtypes. An InConfiguration instance of each protocol/application is created by the SCP when the session negotiation is initiated. Once the session negotiation is complete, the configured values of the InConfiguration instances are stored by the AT and AN at a given personality index. After configuring the multiple sessions, the AN informs the AT about the session to be used using a configuration complete or soft configuration complete message (personality index corresponding to the session to be used is encoded in session configuration token which is sent in configuration complete or soft configuration complete message).
Session configuration can be initiated by the AT or AN.
A protocol revision defines a default set of protocol/application subtypes, which are used by the AT until the session configuration. In the current EVDO system, only one default set of protocol/application subtype exists. At Power Up, the AT creates InUse Instances corresponding to this default set of protocol subtypes. AT's InUse instances are changed from the default to non-default subtypes only by session negotiation.
In the current EVDO communication system only one default set of protocol/application subtypes exists. At power up the access terminal creates InUse instances corresponding to the default set of protocol/application subtypes. AT's InUse instances can be changed from default to non-default subtypes only by session negotiation.
In a multi-protocol revisions system, there is a need to have multiple default sets of protocols. So that the new deployments can directly operate on a system specific to a protocol revision without having to support all previous revisions of the system. Even AT's can be implemented only for some protocol revisions.
In the current system there are no defined procedures for interworking in a system in which the AT is moving across the ANs supporting different protocol revisions of the system.
Therefore, there is a need in the art for techniques or mechanisms which will allow the AT and AN to operate efficiently in a multi protocol revision system.